Optical discs (including magneto optical discs) such as the Compact Disc (CD), the Mini-Disc (MD), the Digital Versatile Disc (DVD), the BLU-RAY Disc (registered trademark), and the like, for example, are known as recording media that record and play back digital data.
“Optical disc” is a generic name for a recording medium in the shape of a circular disc in which a thin metal plate is covered by plastic and from which a signal can be read by shining a laser beam onto the disc and reading the changes in the reflected beam.